Estimates for the displacement of the phase equilibrium lines for small carbon particles containing from several hundred to several tens of thousands of atoms are made, and an error analysis of the uncertainties in these estimates is derived and evaluated using available experimental data. Hugoniot calculations for methane, benzene, polyethylene, and polybutene, based on a carbon particle surface energy adjusted equation of state, are in better agreement with shock pressure-volume and temperature data than those obtained with a bulk carbon equation of state. The results suggest that carbon particles, of order 10(3)-10(4) atoms, can exist in the liquid state at lower temperatures than bulk carbon.